Weather is defined by the American Heritage Dictionary as “the state of the atmosphere at a given time and place, with respect to variables such as temperature, moisture, wind velocity, and barometric pressure.”

Similarly, the term “space weather” is used to describe the state of the environment in space.

But space looks so empty, what kind of weather could possibly be going on?

In space, the sun puts out something called the solar wind; a continuous stream of particles that flows out from the sun.

During what are called solar flares and coronal mass ejections, highly energized particles are shot out from the sun into the solar wind.

Such changes in the solar wind cause changes in Earth's magnetic field.

These are called geomagnetic storms.

Just like thunderstorms on Earth, these geomagnetic storms are more likely at certain times.

Right now, activity on the sun is very quiet, but that will soon be changing.

The solar cycle is the 11-year cycle of activity on the sun.

There are more active periods and quieter periods.

"In the last month, there have been the first signs of the new solar cycle just starting,” says Dr. Stan Solomon, Deputy Director of the High Altitude Observatory at the National Center for Atmospheric Research.

That means that in about 4 or 5 years, geomagnetic storms could be much more frequent.

One of the most obvious and beautiful effects of such storms is the northern and southern lights.

But the same disturbances that cause such beautiful light displays can also endanger astronauts, cause errors in GPS signals, cause power failures, cause problems for flights over the poles, and damage satellites or change their orbits, among other things.

“As solar activity picks up, there will be a host of interesting issues for people to deal with, most of them will affect people who are operating things in space,” says Solomon.

So right now, scientists are developing better ways to forecast geomagnetic storms so that more advanced warnings can be given to those at NASA, aviation interests, and others who need to know when these storms are coming.

Since the solar cycle has been a very predictable phenomenon for centuries, scientists rely on it to forecast periods of activity on the sun.

They are also able to monitor what’s happening on the sun; so they often know a day or so in advance that a geomagnetic storm is coming.

However, with things like space exploration and high-precision GPS technology expanding, longer-term geomagnetic storm forecasts are going to be in high demand, so scientists are researching ways to make such longer-term forecasts.